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61.
In this paper, a mathematical model is developed for the maneuvering motion of a naval ship and bifurcations of its equilibrium are identified in roll-coupled motion. The subject ship is a high-speed surface combatant with twin-propeller twin-rudder system. Captive model tests are conducted for the ship using planar motion mechanism. Maneuvering coefficients are calculated by polynomial curve fitting of the test data. Uncertainty distribution in the coefficients is assumed same as that of the curve fitting errors. Uncertainty in the model coefficients is propagated to full-scale simulation results by the stochastic response surface method (SRSM). This method is computationally efficient as compared to standard Monte Carlo simulation technique. The SRSM uses polynomial chaos expansion of orthogonal to fit any probability distribution. Bifurcation analysis of the mathematical model is performed by varying the vertical center of gravity as the bifurcation parameter. Hopf bifurcation is identified. It is found that the bifurcations occur due to the coupling of roll motion with sway, yaw motion and rudder angle. In the presence of wind, roll angle response in bifurcation diagram is discussed.  相似文献   
62.
This paper describes an integrated methodology for identifying potential ‘quick wins’ for mode shift from road to passenger rail transport. Firstly, a procedure for analysing rail’s relative competitiveness in the market for passenger transport between large urban areas is developed and then applied to a UK case study. The purpose of such analysis is to allow the identification of flows where rail is currently relatively uncompetitive (in terms of journey time in particular) and to assess the reasons for this poor performance, so that the issues which suppress rail use may be addressed. In parallel, a framework, methodology and tool for the assessment of existing and potential capacity (trains, seats, TEUs, etc.) is developed for both passenger and freight traffic, to identify and address network constraints. An illustrative example of the use of these demand and capacity assessment tools is then presented, with the tools used to identify and evaluate flows where rail demand is suppressed by poor service quality and where spare capacity exists which would allow the passenger rail service to be improved without requiring significant investments in infrastructure. The effects of such improvements on demand are predicted, and the cost implications of operating such additional services are discussed. The analysis suggests that there may be significant potential for increasing rail’s mode share by providing additional inter-urban services where rail currently offers an inferior service.  相似文献   
63.
"公交都市"是为了缓解小汽车的快速增长和交通拥堵问题所采取的城市交通战略.本文以湛江市为例,分析得出该市公交发展还存在着基础服务水平低、城市建设与公交发展不协调、公交优先战略未真正落实、智慧公交驱动力不足等问题,阻碍着城市与交通体系建设的有序发展.本文将智慧治理理念与公交都市创建在价值层面与技术层面进行结合,并借鉴新加坡与山东青岛的公交都市发展经验,从理念层面、技术层面与智慧管理层面提出适合湛江市公交都市创建的路径,推动城市公交的人性化、智慧化发展.  相似文献   
64.
This paper summarizes the results of monitoring animals killed by vehicles on selected roads in the Czech Republic as well as the circumstances of these accidents. Relationships between species of road-killed animals and factors associated with these accidents were evaluated, such as type of road and traffic density, distance from the built-up area, state of vegetation around the road, terrain topology with regard to the road, and the impact of the month/season.  相似文献   
65.
本文通过研究国内外相关文献,对公交社区涵义进行解读和界定,依据国内外公交社区的分类和形式,研究国内外公交社区的发展状况,尤其一些经典的优秀案例,最后总结公交社区规划的三大要素。  相似文献   
66.
In this study, stated preference data is used to derive estimated values of commuting time (VOCT). Both spouses in two-earner households are individually making trade-offs between commuting time and wage; both with regard to their own commuting time and wage only, as well as when both their own commuting time and wage and their spouse’s commuting time and wage are simultaneously changed. Thus, we are able to compare how male spouses and female spouses value each other’s commuting time. When only ones own commuting time and wage are attributes, the empirical results show that the estimated VOCT is plausible with a tendency towards high values compared to other studies, and that VOCT does not differ significantly between men and women. When decisions affecting commuting time and wage of both spouses are analyzed, both spouses value the commuting time of the wife highest. Further analysis show that this result is driven by households where the man has the highest income. If VOCT were to be gender specific in policy implications, the value might be higher for women than for men in two-earner households.  相似文献   
67.
Here, a numerical optimization procedure is proposed for a fundamental study of a fast catamaran, and we compare the wave-making characteristics of a catamaran hull form with and without large bow and stern airship-type bulbs installed on the center plane of a catamaran operating at high speed. The method involves coupled ideas from two distinct research fields: numerical ship hydrodynamics and a nonlinear programming technique. The wave-making characteristics of catamaran hulls with and without bulbs were investigated using the panel method applied to free surface flow (PAFS), in which Morinos method for lifting bodies is extended to analyze the problem of free surface flow, and PAFS is linked to the optimization procedure of the sequential quadratic programming (SQP) technique. An optimum hull form for a catamaran can be obtained through a series of iterative computations, subject to some design constraints. Here, only the hull shape of a catamaran is optimized with and without center-plane bow and stern bulbs. The optimization is carried out at two Froude numbers, 0.45 and 0.5, which are around the last hump of the wave-making resistance curve. The numerical results show that a reduction in wave-making resistance is achieved around the design speed.  相似文献   
68.
This study investigates the determinants of peoples desire to increase or decrease the amount of travel they do. We use data from 1,357 working commuters, residents of three different neighborhoods in the San Francisco Bay Area, California. The dependent variables are indicators of Relative Desired Mobility for ten categories of travel (short- and long-distance overall and by several mode- and purpose-specific categories). These variables are measured on a five-point ordinal scale ranging from much less to much more, through which the respondents indicated the amount of travel they want to do (in the category in question) compared to what they are doing now. Censored ordered probit models were developed for these variables, with explanatory variables including general travel attitudes, specific liking for travel in each of the same separate categories, objective and subjective measures of the amount currently traveled in each category, and personality, lifestyle, and socio-demographic characteristics. The results support the hypotheses that the liking for travel has a strong positive impact, and subjective qualitative assessments of mobility have a strong negative impact, on the desire to increase ones travel. Finally, a number of general types of effects on Relative Desired Mobility were identified, among them complementarity and substitution effects. The results of this study can provide policy makers and researchers with new and valuable insight into key principles that affect individual travel demand.  相似文献   
69.
This paper is devoted to the problem of improving network performance to withstand incidents such as earthquakes, which have long-term adverse-effect upon the networks. A measure of link importance is presented based on consumers surplus. This measure is then used to define and solve a network improvement problem. Computational complexities are reduced by introducing an approximate measure of link importance which performs almost as good, and hence may be used for solving large scale problems. Several example networks are used to clarify the discussion numerically.  相似文献   
70.
The paper focuses on how trip time variability affects re-scheduling of daily activities. A delay in a trip or an early arrival can contribute to changes in the timing, location of the next activity, and to the deletion/addition of some activities. We propose the idea of using fuzzy logic rules to explain the effect of variability in travel time on the benefits perceived by an individual with the changes, and to model different actions that the individuals take in order to re-establish the steadiness of the existing timetable. The fuzzy model is used to handle the imprecision of the data which is unstructured text. The results show that large deviations in trip duration are more likely to induce significant changes in the timetable whereas small deviations are either ignored or translated into modified timing of the next activity. In choosing an action, greater importance is assigned to the flexibility of the following activity, to the magnitude of the trip time saving/delay, and to the duration of the next activity. Time savings are not favoured unless they can be readily transferred into additional activity time allocated to the next activity or to a new activity. The fuzzy rules based system is capable of predicting satisfactorily the strategy of coping with uncertainty in travel times and the satisfaction sensed with the change.  相似文献   
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